DESCRIPTION: (Candidate's Abstract) The overall goal of this application is to develop research skills for independent patient-oriented (clinical and fundamental) investigations through (a) didactic courses, (b) special studies and (c) intensive supervised research. The candidate for this K23 award has completed 2 years of Ph.D. training in physiological optics and vision science, and is conducting psychophysical research on amblyopia with Dr. Dennis Levi. The specific training aims are to develop research skills and experience in (1) psychophysics, (2) computational vision, and (3) functional magnetic resonance imaging (fMRI). Amblyopia is a major cause of vision loss in infants and young children. Amblyopia results in well-documented losses in detection of luminance defined patterns that reflect abnormalities in primary visual cortex (VI). The Levi lab has recently shown losses in detection of contrast defined (second-order) patterns, which are widely believed to be processed in early extrastriate visual cortex (V2). The specific research aims test hypotheses about the mechanisms of these second-order spatial losses in amblyopia. Is the V2 loss associated with (la) loss of binocularity, abnormalities in (1b) compressive non-linearity, (1c) contrast gain control, (1d) long-range interactions, and (le) predictable by a quantitative model? Are abnormal mechanism(s) explained by (2) reduced second-order neuron population in V2? The research design includes psychophysical experiments (aims la - ld), computational modeling and simulation (aim le), and brain functional magnetic resonance imaging (fMRI) (aim 2) on normal and amblyopic human adults. Understanding amblyopia and its neural basis may lead to improved diagnosis and treatment.